Topic outline

  • Chapter 14 – Chemical Effects of Electric Current – 4

    • Chemical Effects of Electric Current – Questions Page

      Chemical Effects of Electric Current

      Q41. The bulb does not glow in the setup shown in Figure. List the possible reasons. Explain your answer.


      Image from NCERT

      Ans. The bulb may not glow because of the following reasons:

                               i.        The connections of wires in the circuit may be loose.

                              ii.        The bulb may be fused.

                             iii.        The battery may be used up.

                             iv.        The conductivity of liquid may be very low.

                             v.        The liquid may be non-conductor of electricity.



      Q42. The process that you saw in Activity 14.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of battery and why?

      Ans. A thick rod of impure copper should be connected to the positive terminal of the battery. A thin plate of pure copper should be connected to the negative terminal of the battery. On passing electric current, the metal dissolves from the impure anode and goes into the electrolyte solution. The positively charged ions of metals present in their molten compounds are attracted by the negatively charged electrode.

       

      Q43. How would you classify lemon juice- a good conductor or a poor conductor of electricity?

      Ans. When the lemon juice between the two ends of the tester allows the electric current to pass, the circuit of the tester becomes complete. The current flows in the circuit and the bulb glows. This shows that lemon juice- a good conductor of electricity.

      From NCERT



      Q44. A beaker contains an acidified copper sulphate solution. A copper plate and a carbon rod are kept in this copper sulphate solution. The copper plate is connected to the positive terminal of a battery whereas the carbon rod is connected to the negative terminal of the battery. What happens when electric current is passed through copper sulphate solution?

      Ans. When electric current is passed through the copper sulphate solution, copper sulphate dissociates into copper and sulphate. The free copper gets drawn to the electrode connected to the negative terminal of the battery and gets deposited on it. From the other electrode, a copper plate, an equal amount of copper gets dissolved in the solution. Thus, the loss of copper from the solution is restored and the process keeps going. This means that copper gets transferred from one electrode to the other.

       

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